Children's Commissioner for Wales Keith Towler said the survey was a wake-up call for adults.

The survey, conducted in 2005-6 across 40 countries, looked at aspects of health, including drinking, weight, smoking, school pressures and bullying.

It found more 15-year-old girls in Wales had tried cannabis than anywhere else in Europe.

Among girls, one in five 11-year-olds in Wales are trying to lose weight, as are a quarter of 13-year-olds and nearly a third aged 15.

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More than a third of 15-year-old girls and a quarter of 15-year-old boys in Wales say they tried smoking at 13 or younger, figures which are similar to Scotland but higher than England.

The survey found children in England and Wales were under more pressure than almost every other country which took part.

Researchers said children in the UK rated their own health "poorly" compared to other countries, and found it harder to talk to their parents.

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Wales tops list of teenage 'drunkenness'

A spokesperson for the chief medical officer for Wales, Tony Jewell, said: "Reports with a global outlook, such as this, play a vital role in highlighting key health matters that occur here in Wales and support the minister and officials to tailor effective policy to tackle such issues.

"Reducing the underage consumption of alcohol is a key priority in Wales.

"The increasing culture of binge drinking in Wales' youngsters leads to greater risk of injury, unsafe sex, and serious health issues in later life that will inevitably put greater pressure on the NHS.

As adults we have got to think of our responsibilities to children and what example we are setting

Keith Towler, Children's Commissioner for Wales

"The Welsh Assembly Government launched a 10-year substance misuse strategy in February. By 2010-11, £27m a year will be funded to the strategy which will place a significant focus on the inappropriate and risky use of alcohol, instances of which are higher in Wales than most other countries, although less so than in recent years."

But Mr Towler said the emphasis now had to be on putting the policies into practice.

"I was at the United Nations committee last week on the rights of the child and we talked about how good some of the policies and strategies are that we have in place particularly in Wales and through the Welsh Assembly Government," he said.

"But we really still are not seeing implementation of these strategies on the ground."

Mr Towler also said the survey also highlighted problems with the availability of services for children and young people in Wales.

He was also critical about the way alcohol was marketed and he called on adults to set a better example.

"The whole of our culture is based on drinking," he said. "As adults we have got to think of our responsibilities to children and what example we are setting."

Kathryn Allen from Promo Cymru, which is a social enterprise and youth development organisation, said that having a drink was often cheaper for young people and children than going to the cinema in the evening.

"There are pubs on every corner, there are shops everywhere selling cheap alcohol and we have the issues with binge drinking. This is a society issue," she said.

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